Core Wars

It's so common to see computers advertised with "Quad-core power!", and then see that in fact the computer has the budget Core 2 Quad Q6600 processor. Remember the megahertz wars, where processor clock speeds increased because consumers thought bigger numbers were always better?

Now we're seeing the Core Wars. How much faster is a Q6600 than a Core 2 Duo E6850? If you're a scientist, the Q6600 would be faster. If you're an ordinary desktop user, even if you encode video, you'll probably find that the E6850 is faster.

Most consumers don't realise that their programs are single-threaded, and thus won't take advantage of extra processing cores. Most consumers don't know the difference between CPU and IO-bound activities - I often hear people saying "You could have a core dedicated to your virus scanner", forgetting both that virus scanning is an IO-bound activity primarily (is limited by your hard disk's speed), and that the user cannot make decisions about what core is used for what activity.

The Q6600 has four cores, each at (I believe) 2.2GHz. The E6850 has two cores at 3GHz each. Sure, if you tally them up, the Q6600 has "6.6 GHz" and the E6850 has "6 GHz", but it doesn't work that way. When I run a video editing program and tell it to use multiple threads for my multiple cores, I still find that the CPU only gets up to about 60-70%. One core is maxed out, the other core is moderately worked. If you had a quad-core machine, you'd find that two cores are maxed out, because the speed per core is lower.

Or, let's look at MP3 encoding. I think this is a single-threaded activity. If you have an E6850, you have a 3 GHz core working to full capacity. If you have a Q6600, you have a 2.2GHz core working to full capacity. MP3 encoding does not paralellise to multiple cores. What is faster? The dual-core!

Yes, I've been talking about clock speeds as the comparison, but these processors are still the same microarchitecture, where you *can* compare clock speeds as indicators of performance.

I'd like to see advertisements say "Top-of-the-range Core 2 Duo!" or even "3GHz dual-core!", but then I guess it's more difficult to sell computers based on what is actually better for the consumer, rather than what sounds more impressive. It's not like it costs anyone anything to put in a good dual core rather than an entry-level quad core, as they are the same price. Until we see better SMP-ness in operating systems and applications, I'll continue to recommend good dual cores over basic quad cores.

Comments

[Christopher]

Can't be bothered to go into the "edit" screen. Actually, since the Core 2 Quads are still the old 65nm process and the Core 2 Duos have moved to the 45nm process, there would be extra speed and power efficiency savings for the dual core.

Plus, the Quads have remained the same prices, but the new Duos are cheaper (the replacement for the E6850 is about $50 cheaper than the Q6600)! Extra incentive to put in a good dual-core rather than a mediocre quad-core.